Hi,
I am having problems with the port B. Its an output port and I am writing the whole port. My code is as follows
ORG 2000 LDAA $# FF STAA $1004
Now, if I write 00 hex or FF to theport. The port is always floating. I tried pull ups and pull downs but no difference. Please advice. Thanks
Regards John
The 68HC11 that I worked with allowed you to program the direction of the port -- with the direction bit flipped one way (0 IIRC) the port was a high-impedance input, and with the direction bit flipped the other the port was an output. Most of those ports could also be configured for open-drain output, if you so desired.
Not PORTB.
Take a look at the data sheet, and look for the "Data Direction Register", or DDR. You'll need to configure the port as "output".
In case you're trying to do this without a data sheet, here's one:
Also, are you trying to run it in expanded or special test modes?
Good Luck! Rich
PORTB is not bidirectional and has no DDR.
So, the OP is Simply Out of Luck. )-;
Thanks, Rich
Well, yes and no. He wants to treat it like an output, so I guess it is fortunate that PORTB is an output only port, but if it is truly "floating" then he is screwed. ;)
Register",
And in expanded mode it outputs low order address bits. Could that be your problem?
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